1. Field
The present disclosure relates to a method of screening a lactate dehydrogenase mutant, a lactate dehydrogenase mutant, a polynucleotide, a vector, a microorganism including the lactate dehydrogenase mutant, and a method of producing lactate using the microorganism.
2. Description of the Related Art
Lactate is an organic acid widely used in a variety of industrial fields, including food, pharmaceutical, chemical, and electronic industries. Lactate is a colorless, odorless, water-soluble, low-volatile compound. Lactate is not toxic to the human body and is used as a flavoring agent, a sour taste agent, a preserving agent, or the like. Additionally, lactate is used as a source for a polylactic acid (PLA) that is an environmentally friendly, biodegradable plastic known as an alternate polymeric material.
Technically, PLA is a polyester-based resin obtained by ring-opening polymerization of a dimer lactide for polymerization. PLA may be variously processed into a film, a sheet, a fiber, an injection, etc. Thus, demands for PLA as bioplastics have recently increased to replace existing general petrochemical plastics, such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), or polystyrene (PS).
In addition, lactate includes both a hydroxyl group and a carboxyl group and thus is highly reactive. Accordingly, lactate can be easily converted into an industrially important compound, such as lactate ester, acetaldehyde, or propyleneglycol, and thus has received attention as an alternative chemical material of the next generation for use in the chemical industry.
Currently, lactate is produced industrially by either a petrochemical synthesis process or a biotechnological fermentation process. The petrochemical synthesis process is performed by oxidizing ethylene derived from crude oil, preparing lactonitrile through addition of hydrogen cyanide after acetaldehyde, purifying by distillation, and hydrolyzing using hydrochloric acid or sulfuric acid. The biotechnological fermentation process is used to manufacture lactate in a microorganism from a reproducible carbohydrate, such as starch, sucrose, maltose, glucose, fructose, or xylose, as a substrate.
Under this background, a lactate dehydrogenase mutant and a method of efficiently producing lactate using the lactate dehydrogenase mutant are needed.